This invention relates to a pipe repair clamp and in particular to a flexible band repair clamp for repairing breaks in water or sewer mains.
Watermains and sewer force mains are made of various materials such as cast iron, ductile iron, asbestos cement, P.V.C., steel and, in some municipalities, wood. In the event of a break in a mains, a repair is necessary, and one known method of doing this is with a flexible band repair clamp. Many types of repair clamp are known in the art but basically they comprise a one or two piece flexible metal band which encircles a break in a pipe and means to tightly draw the band edges together so as to tightly comprise a gasket around the pipe over the break and on both sides of the break.
Clamping pressure is achieved by tightening nuts on threaded studs or bolts which draw together lug bars secured to the longitudinally extending edges of the metal band, as is well known to those skilled in the art. Some designs use lugs welded to each lug bar with bolts extending through openings in the lugs and some use bolts welded to one lug bar and passing through lugs welded to the other lug bar. In some designs proper alignment of the bolts during the initial installation procedure is difficult and normally requires the efforts of two people. Two piece band arrangements, with diametrically opposite lug arrangements, are difficult for one person to install.
Canadian Pat. No. 719,944 discloses a clamp consisting of two bands and having lugs curved on the front to allow a nut to slide along and snap into place on a flat face. There are, however, no projections to retain the nuts and the guide fingers do not have dual tapers as do the fingers of the present invention. Installation would appear to be considerably more difficult than the clamp of the present invention.
Canadian Pat. No. 726,521 discloses a clamp comprising a one-piece band with the edges bent back and fitted into slots in the lugs. There is no disclosure of the dual-taper feature of this invention and installation appears to be more difficult. There do not appear to be projections to hold the nut washer combination in position for tightening.
Canadian Pat. No. 918,581 shows a clamp having lugs on a base section which are bifurcated to accept the shank of a bolt. The lugs have tabs to keep the bolts from lifting out of the lugs. It does not disclose the dual-guide system of the present invention so that installation would appear to be more difficult.